The dynamic behavior of skin friction and heat release of
a cylinder in pulsating cross-flow are investigated. Existing
analytical solutions are presented as transfer functions versus
frequency, known from control theory. Newly found expressions
are given for Reynolds number ranges, where no appropriate
model exist until now. These expressions are obtained
by the combination of CFD simulation and system identification
In the CFD/SI approach time series are generated by exciting
inlet velocity fluctuations over a wide range of frequencies in
one single CFD simulation. Time series are acquired for heat release,
skin friction and velocity forcing, and then post-processed
with system identification tools. Direct numerical simulations
are conducted for mean flow Reynolds numbers between 0.1 and
40, solving the incompressible Navier-Stokes equations in a 2D
domain using a finite volume approach. The system identification
framework provides methods to identify a mathematical
model for the response in heat release and skin friction to velocity
fluctuations from data series.
It can be confirmed that Bayly’s model for heat release fluctuations
performs well at low Reynolds numbers. Lighthill’s
model, often used in the assessment of Rijke tubes, is more accurate
for high Reynolds numbers, but the time constant was underpredicted
for Reynolds numbers of order 10. For the range above
a Reynolds number of 0.4 a unifying model could be developed.
This model especially excels at Reynolds numbers of order 10.
Available models for skin friction usually match the simulated
data up to a point, but do not give any dependence on Reynolds
number which is corrected here.
The expressions presented allow insight in the physics of the
dynamic behavior of a cylinder in pulsating cross flow and also
facilitate the use of these models in further investigations.
Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016.